The first cavefish in the Dinaric Karst? Cave colonization made possible by phenotypic plasticity in Telestes karsticus

Čupić, Mateo; Marčić, Zoran; Lukić, Marko; Gračan, Romana; Bilandžija, Helena (2023) The first cavefish in the Dinaric Karst? Cave colonization made possible by phenotypic plasticity in Telestes karsticus. Zoological Research, 44 (4). pp. 821-833. ISSN 2095-8137

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Official URL: http://doi.org/10.24272/j.issn.2095-8137.2022.528

Abstract

Cave animals are an excellent model system for studying adaptive evolution. At present, however, little is known about the mechanisms that enable surface colonizers to survive in the challenging environment of caves. One possibility is that these species have the necessary genetic background to respond with plastic changes to the pressures of underground habitats. To gain insight into this process, we conducted a comparative study with the fish species Telestes karsticus, which occurs in a hydrological system consisting of an interconnected stream and a cave. Results showed that T. karsticus resided year-round and spawned in Sušik cave, making it the first known cavefish in the Dinaric Karst. Cave and surface populations differed in morphological and physiological characteristics, as well as in patterns of gene expression without any evidence of genetic divergence. To test whether observed trait differences were plastic or genetic, we placed adult fish from both populations under light/dark or constant dark conditions. Common laboratory conditions erased all morphometric differences between the two morphs, suggesting phenotypic plasticity is driving the divergence of shape and size in wild fish. Lighter pigmentation and increased fat deposition exhibited by cave individuals were also observed in surface fish kept in the dark in the laboratory. Our study also revealed that specialized cave traits were not solely attributed to developmental plasticity, but also arose from adult responses, including acclimatization. Thus, we conclude that T. karsticus can adapt to cave conditions, with phenotypic plasticity playing an important role in the process of cave colonization.

Item Type:

Article

Uncontrolled Keywords:

Maladaptive and adaptive phenotypic plasticity; Troglobionts and stygobionts; Endemic leuciscid fish; Acclimatization; European cavefish; Cave adaptations; Gene expression differences

Subjects:

NATURAL SCIENCES > Biology > Zoology
NATURAL SCIENCES > Biology > Ecology
NATURAL SCIENCES > Biology > Genetics, Evolution and Phylogenetics

Divisions:

Division of Molecular Biology

Projects: